About capacity:Capacity flash memory products are usually shipped in accordance with 1MB = 1000KB, 1G = 1000MB computing, but the operatingsystem using binary arithmetic 1MB=1024KB, 1GB = 1024MB, so there are some differences between the display capacity and standard capacity memory products.This is calculation difference between manufacturer and our PC.
4GB= approximately 3.2GB-3.8GB8GB =approximately 6.9GB-7.3GB 16GB=approximately 14GB-15GB 32GB=approximately 28GB-30GB64GB=approximately 58GB-59GB
About writing and reading speed :16 – 32gb class 10 SDHC;64gb 128gb class 10 SDXC
Package list:1x memory card